Retaining means for adjustably securing the head of a magnetic recording-reproducing means to a supporting cover plate

ABSTRACT

A supporting means for mechanically securing a recordingreproducing head to one side of a cover plate while providing a release means for the head, accessible from the same side of the plate. The recording-reproducing head is integrally formed with a threaded rod extending below the cover plate and resiliently secured by a locking nut having a geared periphery. An adjusting pinion is coupled to the locking nut and has a cylindrical portion extending through the cover plate where it may be turned by a wrench.

United States Patent 1 1 Kudelski 11 3,744,804 451 July 10,1973

[ RETAINING MEANS FOR ADJUSTABLY SECURING THE HEAD OF A MAGNETICRECORDING-REPRODUCING MEANS TO A SUPPORTING COVER PLATE [76] Inventor:Stefan Kudelski, Ch. de la Croix,

1052 Le Mont-sur-Lausanne, Switzerland [22] Filed: Apr. 19, 1972 21Appl. N0.: 245,309

[30] Foreign Application Priority Data Apr. 22, 1971 Switzerland 5855/71[52] US. Cl 274/4 R [51] Int. Cl. Gllb 5/54 [58] Field of Search179/l00.2 C, 100.2 CA;

274/4 A, 11 A, 4 R

[56] References Cited UNITED STATES PATENTS 2,704,426 3/1955 Macaulay85132 R 2,199,802 5/1940 Leitz et al. 85/1 R FOREIGN PATENTS ORAPPLICATIONS 794,974 l/l955 Great Britain l79/l00.2 C

89,875 2/l900 Germany 85/32 R Primary Examinerl-larry N. HaroianAttorney.lames M. Heilman et al.

[5 7] ABSTRACT 6 Claims, 1 Drawing Figure RETAINING MEANS FOR ADJUSTABLYSECURING THE HEAD OF A MAGNETIC RECORDlNG-REPRODUCING MEANS TO ASUPPORTING COVER PLATE In a high-performance magnetophone (orrecordingreproducing magnetic means) it is necessary to provide for firmfixing of the heads while at the same time allowing for this fixation tobe eased so that the heads may be rotatably adjusted and moreover beeasily removable for cleaning, periodic inspection or replacement.

Whereas angular adjustment, which may be advantageously effected bymeans of a support disc, does not pose any problems, the same cannot besaid of the usual supports. In effect, the heads are either fixed upon abridge fitted on the cover plate or else they are fixed directly ontothat plate, a practice which demands a strong elastic pressure. When abridge is used, loosening and dismantling are comparatively easy sinceit suffices to release the bridge, but access to the magnetic tapeadjoining the heads is poor. On the other hand, when the heads are fixeddirectly on the cover plate it is possible either to bear on the headvia the intermediary of a spring or else to exert a central pull throughthe support disc. Fixing by bearing on the heads gives poor resultssince, first it generates stresses in the cover plate and second, thefriction on the head produces a considerable control hysteresis. Fixingby central pull is effected by means of a screw integral with the headand passing through the support disc and cover plate, this screw beingsecured by a nut under the cover plate and bearing upon it via a spring.This latter method certainly provides a pressure without stress orcontrol hysteresis but is extremely inconvenient for removing or slewingthe heads since this demands access underneath the-cover plate. Suchaccess requires a long, complicated, and delicate operation due to thefact that the mechanism of the apparatus, housed under the cover plate,is positioned directly beneath the heads.

Devised with the aim of obviating these drawbacks and providing a headsecuring means without stresses or other troublesome phenomena, while atthe same time allowing the heads to be adjusted or removed withouthaving to act on the cover plate, the present invention relates to adevice for securing the heads of a magnetophone whereby each head issecured directly on the cover plate by the pull of a rod, integral withthe head. The rod passes through the cover plate and engages a retainingdevice placed thereunder, bearing thereon via the intermediary of anelastic element. The retaining device is coupled to a control member,one part of which passes through the cover plate so as to be accessiblefrom outside the latter, while the retaining device, elastic element andcontrol member are retained permanently in place underneath the saidcover plate.

The drawing hereto attached represents by way of example an embodimentof the invention.

The single FIGURE comprised by this drawing is a schematical sectionalview.

In this FIGURE, 1 is the cover plate of a magnetophone while 2 denotesone of the heads of the apparatus whose other parts are not describedsince they do not form part of the invention.

The head 2 comprises, in conventional fashion, a fixing screw 3 passingthrough a support disc 4 upon which the head 2 is seated, the said discbeing rotatably mounted in a housing recessed for the purpose in thecover plate 1 and furnished with suitable means, not shown in thedrawing, whereby it can be pivoted.

The screw 3 passes through the cover plate 1 and engages in a nut 6having a peripheral gear rim. Arranged between the nut 6 and the coverplate 1 are dish-shaped springs 5 secured to the screw 3.

The gear rim 7 of the screw 6 meshes with a pinion 8 having anunderturned intermediate cylinder 9 bearing on the cover plate 1 and asecond cylinder 10 rotatably joumalled in the said plate and risingabove the plate surface. The cylinder 10 has a hex socket for taking acorresponding hex-head key 12.

The nut 6 and pinion 8 are retained in place beneath the cover plate byan appropriately shaped bridge plate 13 secured to the cover plate 1 byscrews 14. The said bridge plate 13 is provided with a hole 15 forpassage of the screw 3.

The device here shown is used as follows: The head 2 is normally securedto the cover plate 1 and in order to release it for turning or removalall that is necessary is to insert the key 12 into the hex socket ofcylinder 10 and turn the latter anticlockwise. When thus turned,cylinder 10 turns pinion 8 which, acting via the gear rim 7, in turnrotates nut 6 which can thereby be unscrewed to whatever extent desired,thereby easing or completely freeing screw 3 and hence the magnetic head2 which is integral with it. If the head 2 is re moved, nut 6 and pinion8 will be retained in place by the bridge plate 13 so that when the head2 is replaced, the screw 3 can be engaged in the nut 6 without anydifficulty. A slight tightening-up of the bridge plate 13 will gentlypress nut 6 against the springs 5 and serve to keep them in place. Whenthe head 2 is loosened it is a simple matter to act on the support disc4 and accomplish the desired amount of angular adjustment. To relock thehead it suffices to turn the cylinder 10 in the opposite direction bymeans of the key 12 and thereby screw nut 6 onto screw 3 to the degreeof tightness desired.

According to this arrangement, it follows that the head is fixed on thesupport disc 4 because of a centreline axial pull, so that no stressesare imposed on the cover plate, and that the fixation thus providedpermits exertion of a strong elastic pressure while at the same timebeing releasable at will so as ultimately to release the head forremoval, and this without any need to strive for access through themechanism arranged beneath the cover plate 1. Adjustment or removal ofthe head can thus be effected from above the cover plate without havingto open up the apparatus. Rigidity is more important than easy access tothe magnetic tape assured by reason of the head being fixed directly onthe cover plate and not partly screened by a bridge. Fi-

. nally, by fixing the heads on the cover plate 1 and dispensing withthe need for access under the cover plate, it is possible to securesubstantial simplification in construction of the apparatus as a whole.

It goes without saying that the keep plate retaining nut 6, springs 5and pinion 8 could be replaced by any other adequate contrivance andthat it would be equally possible to change the arrangement of pinion 8and its control, as also that of nut 6 and its gearing facility 7.

Then too, the gear-rimmed nut 6 can be replaced by a suitable coupling,such as a bayonet joint, in which case the screw 3 will be substitutedby a rod provided with the necessary lugs. In this case the pinion 8 isreplaced by, for example, a bell-crank lever integral with with thehead, passing through the cover plate; a-

threaded nut meshing with the rod for securing the head to the coverplate, said nut including gear teeth on its periphery; a pinion havingits axis parallel to the axis of the threaded rod and including gearteeth meshing with the gear teeth on the threaded nut for turning thenut during a securing operation; a shaft secured to the pinion and inaxial alignment therewith extending through the cover plate, said shaftformed with coupling means for rotary actuation by an external tool;

and a bridge plate secured to the underside of the cover plate forholding the threaded nut and the pinion in place.

2. A device according to claim 1 wherein resilient means are positionedbetween the underside of the cover plate and the threaded nut.

3. A device according to claim 1 wherein said shaft extends above theupper surface of the cover plate and is formed with a shaped axial holefor actuation by a tool.

4. A device according to claim 1 wherein said shaft is formed with atransverse slot for actuation by a screwdriver bit.

5. A device according to claim 1 wherein said threaded rod extendsthrough a hole formed in the bridge plate.

6. A device according to claim 1 wherein said bridge plate is formedwith a turned-up flange which retains the threaded nut and the pinion intheir operating positions even though the threaded rod may be removedfrom the cover plate.

1. A device for securing the head of a recording system to a cover plateby turning a shaft extending through the plate comprising: a threadedrod, integral with the head, passing through the cover plate; a threadednut meshing with the rod for securing the head to the cover plate, saidnut including gear teeth on its periphery; a pinion having its axisparallel to the axis of the threaded rod and including gear teethmeshing with the gear teeth on the threaded nut for turning the nutduring a securing operation; a shaft secured to the pinion and in axialalignment therewith extending through the cover plate, said shaft formedwith coupling means for rotary actuation by an external tool; and abridge plate secured to the underside of the cover plate for holding thethreaded nut and the pinion in place.
 2. A device according to claim 1wherein resilient means are positioned between the underside of thecover plate and the threaded nut.
 3. A device according to claim 1wherein said shaft extends above the upper surface of the cover plateand is formed with a shaped axial hole for actuation by a tool.
 4. Adevice according to claim 1 wherein said shaft is formed with atransverse slot for actuation by a screwdriver bit.
 5. A deviceaccording to claim 1 wherein said threaded rod extends through a holeformed in the bridge plate.
 6. A device according to claim 1 whereinsaid bridge plate is formed with a turned-up flange which retains thethreaded nut and the pinion in their operating positions even though thethreaded rod may be removed from the cover plate.